The state of California does not require you to file for an extension of time to file as the IRS does. California offers an automatic six-month extension for all taxpayers. The extended due date of your return will be October 15, 2019. However, you will not get an extension of time to pay. If you owe tax then you will need to submit a payment of penalties and interest will accrue.
In order to file your 2017 returns, you will need to purchase the software. You are also required to mail your prior year return as it is not eligible for e-file. Click the TurboTax link below if you need to purchase TurboTax 2017.
https://turbotax.intuit.com/personal-taxes/past-years-products/